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NORA Oilheat Technicians Manual

tube, especially when the air tube is long; if they are provided, use them. Buss bars are non-insulated heavy gauge strips of metal that are made by the oilburner manufacturer to the length and shape to fit a certain model of burner; they are not interchangeable with other models. Spring clips are similar to buss bars, except that contact with the transformer is maintained by spring tension. After some time, these clips can lose their tension and prevent proper and desired contact. They should be checked whenever the burner is serviced. Electrodes Electrodes are metal rods made of specialized steels, and partially covered with a ceramic (porcelain) insulator, Figure 9-11. These insulators are usually made in two major external diameters (7/16" and 9/16"). As we can see in Figure 9-13, these porcelains come in various lengths. They may be ordered in individual lengths 4" to 30", or they may be sized on the job through the use of a special tool for cutting the porcelain insulator. The porcelains serve two purposes: They securely position the electrode rods and they serve as insulators, protecting the metal rod against shorting out to the nozzle assembly. These insulators are center bored to fit the metal electrode rods, either 1/8" or 3/32" in diameter. Electrode holders permit secure and correct mounting Chapter 9 Ignition Systems Figure 9-11: Electrodes of the porcelains and electrodes so that, after adjustment, they cannot shift from vibration or other causes and alter their position. In many cases, the electrode holder is incorporated with the air spinner or turbulator. Electrode testing and setting Figure 9-12 shows one method for testing the porcelain insulator of an electrode for spark leakage. A neon test lamp, with one probe touching the ceramic insulator, the other end of the test lamp free, is shown. By moving the one end of the test lamp over the surface of the porcelain, it can be easily determined whether or not the ceramic insulator is Figure 9-12: Electrode test cracked. If the insulator is defective, the neon test lamp will glow when the probe reaches the defect. Figure 9-13 is a setting for electrodes when one is not available from the manu- 9-12 Ignition Systems Do Not Touch Neon Test Porcelains Wire


NORA Oilheat Technicians Manual
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